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Illusion
3 days ago
8

You are camping in the wilderness. After a few days, you are horrified to discover that you did not pack as many batteries as yo

u had planned, and you have no working batteries for your lights at night. Rummaging through the spare parts in the back of your truck, you find an old motor. On the plate, the information claims that the motor operates from 120 V, rotating at 1,600 rev/min, with an average back emf of 80.0 V. You wish to use the motor as a generator to provide a voltage with a peak value of 7.50 V to operate your electric lantern. You attach a hand crank to the armature of the motor. You need to determine the angular speed (in rev/s) at which you must rotate the crank to provide the desired voltage. Model the armature as a flat coil of wire. Notice that the average back emf is provided, not the peak value, so you will need to find an expression for the average back emf of a motor in terms of parameters associated with the armature rev/s Need Help?
Physics
1 answer:
Keith_Richards [2.2K]3 days ago
8 0
Angular speed is calculated as 2.5 rev/sec.
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The parasailing system shown uses a winch to pull the rider in towards the boat, which is traveling with a constant velocity. Du
ValentinkaMS [2425]

Answer:

The force magnitude is  F_{net}= 1.837 *10^4N

and it is directed at 57.98° from the horizontal in a counterclockwise manner.

Explanation:

The problem states that

At t = 0, \theta = 20^o

The angular rate of increase is w = 2 \ ^o/s

Converting to revolutions per second gives us  \theta ' = 2 \ ^o/s * \frac{\pi}{180} =0.0349\ rps

The rope length is defined by

                      r = 125- \frac{1}{3}t^{\frac{3}{2} }    

    At \theta =30^o, Tension T of the rope is 18 kN.

     The weight of the para-sailor is M_p = 75kg

In analyzing the question, we observe that the equation for length can be represented as a linear displacement equation.

 The derivative of displacement results in velocity.

Hence,

           r' = -\frac{1}{3} [\frac{3}{2} ] t^{\frac{1}{2} }

signifies the velocity, and further differentiation yields acceleration.

Therefore,

         r'' = -\frac{1}{4} t^{-\frac{1}{2} }

Now considering the moment when the rope forms a 30° angle with the water,

typically angular velocity is expressed as

                      w = \frac{\Delta \theta}{\Delta t}

where \theta represents the angular displacement.

Next, evaluating the interval from 20^o \ to \ 30^o gives us

                 2 = \frac{30 -20 }{t -0}

making t the focal point.

             t = \frac{10}{2}

               = 5s

At this time, the displacement measures

             r = 125- \frac{1}{3}(5)^{\frac{3}{2} }  

                = 121.273 m

The linear velocity computes to

             r' = -\frac{1}{3} [\frac{3}{2} ] (5)^{\frac{1}{2} }

                = -1.118 m/s

Whereas linear acceleration calculates as

          r'' = -\frac{1}{4} (5)^{-\frac{1}{2} }

              = -0.112m/s^2

Generally, radial acceleration is given by

         \alpha _R = r'' -r \theta'^2

              = -0.112 - (121.273)[0.0349]^2

              = 0.271 m/s^2

Simultaneously, angular acceleration can be represented as

                 \alpha_t = r \theta'' + 2 r' \theta '

Then \theta '' = \frac{d (0.0349)}{dt} = 0

Thus,

             \alpha _t = 121.273 * 0 + 2 * (-1.118)(0.0349)

                   = -0.07805 m/s^2

The resultant acceleration is mathematically denoted as

                a = \sqrt{\alpha_R^2 + \alpha_t^2 }

                  = \sqrt{(-0.07805)^2 +(-0.027)^2}

                  = 0.272 m/s^2

Now the acceleration's direction is mathematically expressed as

                  tan \theta_a = \frac{\alpha_R }{\alpha_t }

                       \theta_a = tan^{-1} \frac{-0.271}{-0.07805}

                           = 73.26^o

               

The y-axis force acting on the para-sailor is mathematically shown as

               F_y = mg + Tsin 30^o + ma sin(90- \theta )

                    = (75 * 9.8) + (18 *10^3) sin 30 + (75 * 0.272)sin(90-73.26)

                    = 9.74*10^3 N

The x-axis force acting on the para-sailor is represented as

              F_x = mg + Tcos 30^o + ma cos(90- \theta )    

             = (75 * 9.8) + (18 *10^3) cos 30 + (75 * 0.272)cos(90-73.26)

             = 1.557 *10^4 N

The overall force is calculated as

                      F_{net} = \sqrt{F_x^2 + F_y^2}

                             =\sqrt{(1.557 *10^4)^2 + (9.74*10^3)^2}

                            F_{net}= 1.837 *10^4N

The directional force is evaluated as

              tan \theta_f = \frac{F_y}{F_x}

                   \theta_f = tan^{-1} [\frac{1.557*10^4}{9.74*10^3} ]

                       = tan^{-1} (1.599)

                       = 57.98^o

     

                     

7 0
22 days ago
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inna [2210]
<span>Answer: The correct response is simply sum the two kinetic energies: E = (1/2)mv^2 + (1/2)mv^2</span>
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15 days ago
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Answer:

Explanation:

The equation used to determine the maximum height of the bowling pin during its trajectory is given by;

H = u²/2g

where u, the initial speed/velocity, equals 10m/s

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Substituting in the values gives us

H = 10²/2(9.81)

H = 100/19.62

Consequently, the highest point of the bowling pin's center of mass is approximately 5.0m.

3 0
1 month ago
A charge of 4.9 x 10-11 C is to be stored on each plate of a parallel-plate capacitor having an area of 150 mm2 and a plate sepa
Keith_Richards [2263]

Answer:2.53*10^-10F

Explanation:

C=£o£r*A/d

Where £ represents the permittivity constant

£o= 8.85*10^-12f/m

£r=6.3

A=150mm^2=0.015m^2

d=3.3mm= 0.0033m

C=8.85*10^-12*6.3*0.015/0.0033

C=8.85*6.3*10^-12*0.015/0.0033

C=55.755*0.015^-12/0.003

C=8.36/3.3*10^-13+3

C=2.53*10^-10F

7 0
22 days ago
When 999mm is added to 100m ______ is the result​
Keith_Richards [2263]

Answer:

The outcome of adding 999mm to 100m is 101m.

Explanation:

That's my belief.

6 0
26 days ago
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